Up to now, as a liquid crystal display apparatus utilizing a transmission type liquid crystal panel, one is proposed with which a dynamic range expansion of a luminance of an image to be displayed is realized by changing an amount of incident light for each of display areas (blocks) on the liquid crystal panel with use of a plurality of back lights (for example, see Patent Document 1).
In this manner, in a case where the light is incident from the respective plural back lights on the respective corresponding display areas of the liquid crystal panel, as shown in FIG. 1, the light amount that should be emitted from the respective back lights is obtained from an image signal of the image to be displayed.
That is, in FIG. 1, an image signal with a step-like wave pattern indicated by an arrow A11 is input to a light emission amount calculation unit 11 and a division unit 12, and in the light emission amount calculation unit 11, on the basis of the image signal, the light amount that should be emitted from one back light 13 is calculated. Also, in the division unit 12, by dividing the supplied image signal by the light amount from the light emission amount calculation unit 11, a transmittance of the light in a display area of a liquid crystal panel 14 corresponding to the back light 13 is calculated. It should be noted that in the wave pattern of FIG. 1, the lateral axis represents a horizontal position of the back light, and a center position represents a center position in the display area of the back light 13.
Herein, as the size of the one back light 13 is larger than the size of a pixel in the display area of the liquid crystal panel 14, the light amount of the back light 13 is calculated from a pixel value of each pixel for the image displayed in the display area of the liquid crystal panel 14 corresponding to the back light 13.
Then, when the light amount is calculated, the back light 13 emits the light on the basis of the light amount calculated by the light emission amount calculation unit 11, and the light is incident on the liquid crystal panel 14. According to this, from the back light 13, a light with a wave pattern indicated by an arrow A12 is projected. That is, as the light from the back light 13 is diffused, the light amount at the center of the light is the largest, and the light amount decreases as being away from the center.
Also, the liquid crystal panel 14 transmits the light from the back light 13 with a wave pattern indicated by an arrow A13, that is, at a transmittance calculated by the division unit 12. According to this, in the display area of the liquid crystal panel 14, as indicated by an arrow A14, an image almost the same as the image of the input image signal is displayed.